Gridcoin - decentralized scientific research

The concept of Proof-of-Work mining is rather simple - set up your miner client, let it run repetitive algorithms. Mint your coins. Rinse, repeat. Gridcoin however takes an entirely different approach - it rewards BOINC computations using the Distributed Proof of Research (DPOR) reward mechanism. In other words, it's mined through computational science which in turn advances scientific research across many different fields. But it gets better - in addition to mining Gridcoins and advancing science, you can make an actual scientific discovery and be credited with it, even if you are an average cruncher (i.e. using only an old PC you have at home).

BOINC->PrimeGrid->Generalized Fermat Prime Search

Probably the quickest way to make such a discovery is to search for new prime numbers, through a BOINC project called PrimeGrid. PrimeGrid has many subprojects, searching both for the largest primes and for the smaller ones, which are of course easier to find and require less computations. One of the PrimeGrid's subprojects which has the best chances of finding a new prime is Generalized Fermat Prime Search or simply Genefer. This search is looking for primes in the form of b^2^n+1 (called generalized Fermat numbers or GFN). When n=15, exponent is 2^15=32768 (as in the title of this post). b value is increasing every day, as the project is going on and new results are coming in. For n=15, maximum b completed is currently 38057562 (slightly higher than the one in the title of this post). Such primes are considered small by today's standards - an average GPU running PrimeGrid will take only a couple of minutes to compute it. Generalized Fermat numbers with larger exponents (largest is currently with n=22) take 2-3 days to compute on high-end GPUs, but can potentially lead to a discovery of the second largest prime number known so far. That particular subproject is called Generalized Fermat World Record Prime Search.

                                     

37919898^32768+1 is prime

My desktop PC discovered this generalized Fermat prime a few days ago. I received this e-mail from PrimeGrid to inform me about the discovery:

Dear Primefinder,

Congratulations! Our records indicate that a computer registered by you has found a unique prime number. This computer is running BOINC, is attached to the PrimeGrid project, and is assigned to the Generalized Fermat Prime Search n=15 (GFN-15). Since candidates on this subproject are not large enough to report to the Top 5000 Primes List, your prime is visible immediately.

Workunit 502641412 : 37919898^32768+1 (248 345 digits)

If you have any questions or concerns, please contact us and we will surely resolve any problems. Once again, congratulations on your find! Thank you for participating in PrimeGrid.

PrimeGrid staff

When you click on the workunit link, you are presented with full details from the PrimeGrid database:

My computer is 293682, it received this workunit at 12:35:07, crunched it in 184 secs and returned the result at 12:38:29, beating the other computer for only 6 minutes. That's an important detail, because the computer which first submits the result is considered to have made the discovery, the other is just a doublechecker and this workunit was a close call indeed. As you can see, the other computer was actually faster in processing the workunit, but it probably had a larger workunit queue, so this valuable workunit containing an undiscovered prime-number wasn't processed immediately. My PC, on the other hand, started processing it as soon it was downloaded, because PrimeGrid is really just a secondary BOINC project for me, running only when work for MilkyWay@home isn't available, so I intentionally adjusted my PrimeGrid workunit queue depth to zero.

You can also click on numbers in the Computer column to get more details about the machines which processed this workunit and discovered a prime. I used AMD Radeon HD7970 to compute it and the other cruncher (recoil44) used a Nvidia Quadro K620: 

Quadro K620 is a workstation graphic card and actually has much lower computing performance than HD7970, but for such relatively small prime numbers, differences are usually caused by drivers, memory speed and PCI Express bandwidth, not by raw GFLOPS of the GPU. Such differences are usually small, most GPUs will be able to process such workunits in 2-4 minutes, meaning that almost everybody can participate with their PCs. Only very old graphic cards which don't support OpenCL cannot be used for PrimeGrid and, in turn, for mining Gridcoins.

You can also click on the numbers in the task column, to get more details about the software used by PrimeGrid to crunch this workunit:

Probably the most important thing to note here is that the so called OCL4 transform was used, which is FP32 (single-precision). Some other PrimeGrid transforms use FP64 (double-precision), but that's really a topic for another lengthy post.

10223*2^31172165+1 is also a prime

More interested in large prime numbers? You are in luck: just a few days ago, on 31 October 2016, PrimeGrid discovered its largest prime number so far, ranked 7th overall. This prime is 9,383,761 digits long and an Intel i7-4770 CPU needed almost 9 days to fully crunch it (within a different PrimeGrid subproject, using only CPU applications). This Mega Prime was enough to propel the lucky discoverer (nicknamed SyP) firmly to the top of PrimeGrid's Top Prime Finders list. You can find the full report on this discovery here (PDF).

Conclusion

As you can see, the world of computational science can be quite complex, competitive and interesting, certainly a lot more interesting than the world of Proof-of-Work hashing! There are a lot of details and factors which can affect the BOINC performance of your PC (and the amount of Gridcoins mined in turn). And we really covered not even one BOINC project, but just one subproject (GFN-15) and one small aspect of Gridcoin GPU mining. For some quick info about other BOINC projects rewarded by Gridcoin, you can visit Gridcoin's forum on Cryptocointalk.